Avoid Hasty Abstractions (AHA)

Duplication is cheap. The wrong abstraction is expensive — it infects every caller with parameters, flags, and conditionals that grow forever.

"Prefer duplication over the wrong abstraction." — Sandi Metz

The Core Rule

• 2 occurrences: leave them duplicated.
• 3 occurrences: consider extracting — only if the shape is obvious and the name is clean.
• Can't name it cleanly? It's not an abstraction yet. Leave it duplicated.
• Extracting requires a flag/mode/boolean? Wrong abstraction. Inline it back.

The Failure Pattern to Recognize